For three days next month, independent scientists will explore whether a child with asthma in urban North Texas might be in more danger from smog than previously thought. They’ll consider whether the summertime ozone inhaled by an outdoor worker in Houston, an Atlanta retiree or a healthy, active adult in scores of places might be harmful even at levels too low for the breather to notice.

And they’ll ponder whether the nation should do something about it.

Indications are that the scientists will answer yes.

If so, they’ll provide a historic push for an effort that has stalled for six years: adopting the toughest clean-air standard in the nation’s history, one that backers say has broad scientific support.

Dallas-Fort Worth would be an important test case for whether the nation needs to scrub more ozone, or smog, from the air.

“It depends upon how low they go, and also the time frame that’s given to attain that standard,” said David Brymer, director of the Texas Commission on Environmental Quality’s Air Quality Division.

Figures show the region’s air quality has improved even as the population has grown — the argument made most often by Texas officials.

Texas fought the last proposed federal crackdown on ozone and would be expected to fight a new one.

The numbers, however, also show that North Texas’ summer ozone is still unhealthy when measured by the existing federal standard. Doctors say they see the proof in their offices and emergency rooms after higher-than-usual ozone days.

Researchers back up the anecdotal accounts with epidemiological studies of Dallas-Fort Worth and other urban areas.

Mounting evidence

Meanwhile, a large and growing body of scientific evidence argues that healthy lungs require much cleaner air than the existing standard could provide even if every city achieved it.

That’s based on studies reporting that it takes less ozone to trigger an asthma attack, shortness of breath or even death in sensitive individuals than researchers once believed.

The groups always known to be at greatest risk — children in general, children with asthma and the elderly — still face particular danger.

As research continues, new groups with special risks have joined them: people with low intakes of vitamins C and E, people with certain genetic traits linked to respiratory inflammation and those who work outdoors.

In some studies, healthy adults have been found to be at risk.

There is also increasing confidence that ozone is linked to deaths.

The evidence of harm has survived numerous public grillings. If it keeps prevailing, the message will be that Dallas-Fort Worth has much further to go to achieve healthy air than current plans suggest.

The ozone panel is scheduled to convene March 25-27 in Chapel Hill, N.C., to review second drafts of EPA papers on human and environmental exposures and on the findings’ policy aspects.

Based on members’ comments on earlier drafts of EPA assessments, there is significant scientific backing for a tighter standard — perhaps a much tighter one.

Alternative standards

Dr. Ana Diez-Roux, a professor of epidemiology at the University of Michigan and a panel member, wrote that there is “abundant evidence of important health effects below the current standard.”

The science, she wrote, “suggests that a range of alternative standards certainly as low as 60 ppb (and even 50 or 55 ppb for comparison purposes) should be explored.”

Other panelists mentioned 60 to 70 parts per billion, which was the outside science advisers’ unanimous recommendation to the George W. Bush administration’s EPA chief, Stephen Johnson, in 2008.

Johnson rejected that recommendation and set the standard at 75 parts per billion, a decision widely condemned as not protecting public health. It is that more lenient standard that Dallas-Fort Worth has been unable to meet.

As with any scientific debate, there are dissenters. One is Michael Honeycutt, chief toxicologist for the Texas Commission on Environmental Quality.

Honeycutt testified against then-EPA Administrator Lisa Jackson’s move to tighten the ozone standard in 2011. President Barack Obama later put a new standard on hold until now.

And last year, when the Dallas County Medical Society and the Texas Medical Association asked the TCEQ to force a phase-out of three old, coal-burning power plants within five years, Honeycutt supplied commissioners with a list of studies he said showed there was no health-based need.

The commissioners agreed and turned down the doctors, who were represented by Dr. Robert Haley, noted epidemiologist and professor at UT Southwestern Medical Center in Dallas. Haley is now reviewing the studies Honeycutt provided.

In an interview last week, Honeycutt said his TCEQ division has submitted a paper for publication that finds no decrease in supposedly ozone-related health concerns as ozone levels have decreased. If ozone hurts people, he said, less ozone should mean fewer sick people.

“You just don’t see it,” he said.

He acknowledged, however, that his is a minority view. Asked if he expected to prevail against what seems to be strong momentum among scientists for a stricter standard, Honeycutt said no.

The fights over ozone that get the most attention usually involve the economy. When Obama shut down the EPA’s latest ozone proposal 2½ years ago, he said it would cost too much during a weak economy.

That was the same argument that business and industry groups and Republicans in Congress were making. Cost, however, depends on who’s speaking, since a full accounting includes both the expenses for compliance and the savings from better health.

Science frequently finds itself a proxy in the policy wars. For many interest groups, attacking the scientific integrity of the opponents’ position is a standard tactic.

Avoiding political sway

In the Clean Air Act, Congress sought to buffer science from political influence by mandating outside peer reviews of research findings before the EPA administrator decides on a pollution standard.

The law gives the administrator, currently Gina McCarthy, broad discretion in setting a standard, but she must consider only the health and environmental aspects, not cost. Cost is considered separately when the EPA writes procedures for how to achieve the standard.

The rationale is that a standard is like a doctor’s diagnosis, which should be based on medical test results, not the depth of a patient’s pockets. Cost comes in later when the doctor and patient choose treatment options.

The Supreme Court has twice upheld the ban on considering costs when setting a standard, most recently in 2001. Justice Antonin Scalia wrote then for a unanimous court that the Clean Air Act “unambiguously bars cost considerations from the [standards]-setting process, and thus ends the matter for us as well as the EPA.”

Such decisions give science a starring role in the run-up to a possible new standard, the process underway now.

The work starts with an integrated review plan produced by EPA experts. Then the agency’s air research and development staff reads thousands of science journal articles, screening them for relevance and quality.

Those making the cut wind up in an integrated scientific assessment, a detailed summary of what scientists have learned.

“We evaluate the world’s [research] literature,” said John Vandenberg, director of the EPA National Center for Environmental Assessment’s branch in Research Triangle Park, N.C.

Experts from a range of scientific fields read the studies and assemble them into a format that displays the relevant evidence, regardless of what it suggests, Vandenberg said.

“That would include studies that are showing effects on the populations that have been exposed, and studies that did not show effects,” he said.

Other EPA staffers prepare an assessment of risks and exposures, plus a policy assessment that draws from the science and exposure papers to present issues for the agency’s administrator.

“It’s pulling those two threads together to tell a story about whether different standards should be considered,” said Erika Sasser, acting director of the EPA’s Health and Environmental Impacts Division.

The policy assessment is not a recommendation by the EPA staff, Sasser said.

Making recommendations falls to the science advisers. Next month’s meetings could show how they’ll decide.

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